Tuesday, October 26, 2010

So I was creating a video to showcase my cousin's ambient/electroacoustic music and needed the best output possible. I put together the project with scraps of 1080P video from my Canon 5D that I had lying around.

Normally, I would do my edits and then post an MPEG-TS to Vimeo. However, as Florian had called out recently, I found that portions of the final video were slightly underwhelming in quality. Specifically, some timelapses in the video looked grainy. This was because the MPEG2 render parameters I had been using in the above link were giving me less than best quality. So my solution was to use a two pass encode from Cinelerra via the YUV4MPEG stream capability into an MPEG4. Easier said then done.

There are three steps:1) export the audio2) perform the first pass encoding into /dev/null3) perform the second pass encoding with the audio file into the final file

Export the AudioAs I was having some sync issues, I pushed the audio a little further down the timeline using a negative nudge value.

First Pass EncodeCinelerra seems to be very sensitive to any garbage in the command line sent to the YUV4MPEG stream. Look at this output:

That is just damn ugly. It looks like some crap got pasted into the command string. Even though I couldn't see anything at the end of the line in the YUV4MPEG stream, I hit the delete key a few times. The method cleaned out whatever invisible control characters got into the command.

Note that 1) the audio file is not merged at this first pass step.2) there is no output file in the first pass encode, the output goes directly to /dev/null

Second Pass EncodeThe second pass encode string is where I add my audio file and my output. In the second pass encode string below, note the appearance of the audio file path and the % at the end of the YUV4MPEG stream indicating the output file:

Note that I could have done these commands outside of Cinelerra if I had output the video to some intermediate file format, usually Quicktime for Linux with JPEG or MJPEG compression for best results.

Every project I do leads me to find some bit of minutiae that sticks in my brain. This time, the minutiae is an FFMPEG bug wherein the parameter to make adjustments to the audio sync does not work for MPEG4 files:https://roundup.ffmpeg.org/issue359

Final ResultAll-in-all, I think this pain gave some very nice results. Let me know what you think:

Why Mule?

"Mules are not really stubborn. They can seem lazy because they will not put themselves in danger. A horse can be worked until it drops, but not so with a mule. The "stubborn" streak is just the mule's way of telling humans that things are not right. Mules are very intelligent and it is not a good idea to abuse a mule. They will do their best for their owner, with the utmost patience."About Mules